More multi-axis machines

Unicut Precision has added another pair of twin-turret, twin-spindle turn-mill centres for the production of complex components for the hydraulics industry.

The new Miyano BNE-51MSY machines from Citizen Machinery UK join two identical twin-spindle, twin-turret lathes with live tooling and a Y-axis on the upper turret that were supplied at the end of 2017.

Established in 1990, Unicut has been a turned parts subcontractor for most of its existence, progressing to CNC turning in 1993. However, in 2017 the company diversified into prismatic machining with the purchase of a multi-pallet machining cell, followed quickly by a second. A third cell is now on order for delivery later in 2019, which will be a record year for capital investment at £2.3 million.

Over the years, Director Jason Nicholson has bought 104 CNC lathes, 93 of which were either Citizen Cincom sliding-head models or fixed-head lathes from Miyano, which merged with Citizen in 2011. Today, Unicut operates 22 Cincom lathes with up to 13 CNC axes, 80 cutting tools and 2,000 psi coolant pressure, as well as eight Miyano machines deploying up to 72 cutters. The machines are usually replaced every five to seven years to take advantage of the high residual value of the lathes at that age.

The key criteria for each purchase have been the combination of machine cost and achievable cycle times to ensure lowest cost per part produced and the most rapid return on investment.

Unicut’s business model is to approach OEMs, analyse their main cost drivers, investigate the possibility of re-engineering components for more efficient production, establish desired cycle times and then identify machine tools needed to machine components within those times and, subject to a long-term commitment from the customer, make that capital investment to become a strategic supplier.

80% of throughput at Unicut’s Welwyn Garden City factory is produced on this basis.

For machining larger diameter parts, a 51 mm capacity Miyano costs about the same as a top-end 32 mm Cincom slider. Unless a high component length-to-diameter ratio dictates otherwise, Mr Nicholson prefers the fixed-head option based on a number of factors including rigidity, thermal stability, value for money and speed. Bar capacity is greater, offering more flexibility; spindle power is higher, leading to increased productivity; cycle times are comparable; access is easy for setting up, despite the compact machining area; and the Mitsubishi control supports superimposed machining whereby three tools can be in cut at the same time for high productivity.

Once a BNE-51MSY is set, Mr Nicolson said that it will produce a run of say 1,000 components to very high accuracy without having to touch the machine by including macros in the program to offset tools automatically after a predetermined number of parts have been produced. Tolerances down to ± 2 microns can be held and surface finish is described as impeccable.

Mr Nicholson says that the current weakness of the pound against overseas currencies has cut 20%r cent off the price of components that Unicut exports and has boosted turnover, despite raw material and indeed the equipment on which to machine it being more expensive to buy. The firm's first order from China was delivered in August this year and exports overall currently account for 40% of turnover, up from 10 to 30% in previous years.